The present invention relates generally to mobile radios and global positioning systems and, in particular, to a mobile radio with global positioning system capability.
GPS is a world-wide radio navigation system formed by a group of 24 satellites and their associated ground stations. GPS uses these satellites, appropriately called NAVSTAR (Navigation Satellite Timing and Ranging), to calculate ground positions. The basis of GPS operation is the use of triangulation from the satellites. To triangulate, a GPS receiver measures distance using the travel time of radio signals. However, to measure travel time, GPS needs very accurate timing, plus it needs to know exactly where the satellites are in space. To solve this problem, each of the 24 satellites is inserted into a high enough orbit (12,000 miles) to preclude interference from other objects, both man-made and natural, and to insure overlapping coverage on the ground so that a GPS receiver can always receive from at least four of them at any given time. In addition, compensation is inserted for any delay the signal experiences as it travels through the atmosphere to the receiver.
With the satellites operating at 12,000 miles above the earth""s surface, they are arranged in strategic positions and orbit the earth every 12 hours. Each satellite transmits a low-power radio signal in the UHF frequency range; the frequencies used are designated as L1, L2, and so forth. GPS receivers listen on the L1 frequency of 1575.42 MHZ. This signal, since it is line-of-sight, will reach the ground receiver unless it is obstructed by solid objects, such as buildings and mountains.
The L1 signal is accompanied by a pair of pseudo-random signals (referred to as pseudo-random code) which is unique to each satellite. These codes are identified by the GPS receiver and allow for the calculation of the travel time from the satellite to the ground. If this travel time is multiplied by the speed of light, the result is the satellite range (distance from satellite to receiver). The navigation information provided by each satellite consists of orbital and clock data, plus delay information based on an ionospheric model. Signal timing is provided by highly accurate atomic clocks. The GPS receiver uses NAVSTAR satellite signals as a way of determining exact position on earth. Exemplary uses of GPS include security, emergency response, travel guidance, and so forth.
Mobile radios, such as for example those that operate in accordance with the General Mobile Radio Service (GMRS) and Family Radio Service (FRS), are becoming increasingly popular. Such mobile radios can be used to communicate, for example, when vacationing, hiking, biking, walking, driving, hunting, fishing, and so forth.
GMRS and FRS are two-way voice communication services. GMRS includes 23 channels, and FRS includes 14 channels. The first seven GMRS channels are on the same frequencies as the first seven FRS channels. Thus, the user of a GMRS mobile radio can communicate with the user of a FRS mobile radio, but only on the first seven GMRS channels. While GMRS requires a license from the Federal Communication Commission, FRS does not.
GMRS and FRS are only two of many radio services. For example, there are six Citizen Band Radio Services including FRS.
However, while handheld GPS devices and mobile radios provide useful features and services to users of the same, there is still a need for a mobile radio that can communicate its position (and hence the position of its user) to other, similar devices.
The problems stated above, as well as other related problems of the prior art, are solved by the present invention, a mobile radio with global positioning system capability.
According to an aspect of the present invention, there is provided a mobile radio with Global Positioning System (GPS) capability. A GPS receiver receives position information from GPS satellites for presentation to a user of the mobile radio. A mobile radio transceiver transmits and receives radio frequency (RF) signals. The RF signals include at least one of speech and the position information.
According to another aspect of the present invention, the mobile radio further comprises a user input device for selecting between a mobile radio mode, a GPS mode, and a mobile radio with GPS mode.
According to yet another aspect of the present invention, the mobile radio transceiver transmits an utterance of a user of the mobile radio to at least one other mobile radio with GPS capability.
According to still yet another aspect of the present invention, the mobile radio transceiver transmits an utterance of a user of the mobile radio to at least one other mobile radio without GPS capability.
These and other aspects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which is to be read in connection with the accompanying drawings.